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| United States Patent |
5,017,374
|
|
Humphrey
|
May 21, 1991
|
Crop growth promotion
Abstract
This invention relates to a seed dressing material for application to seeds
of plants adapted to be grown in an environment with or without
legume-growth-factor, to enhance the trace mineral uptake or growth of the
plants. This material comprises effective amounts of fungal spores of the
family Coprinus, preferably spores of Coprinus comatus, and a further
ingredient selected from GTF chromium and yest, or combinations thereof.
The plants resulting from the growth of seeds treated with the dressing
material of this invention reach maturity faster, and have increased
contents of zinc and chromium, both necessary dietary trace elements for
mammals.
| Inventors:
|
Humphrey; Robert E. (Aylmer, CA)
|
| Assignee:
|
Agro Elements (Toronto, CA)
|
| Appl. No.:
|
182007 |
| Filed:
|
April 15, 1988 |
| Current U.S. Class: |
424/93.5; 47/57.6; 47/DIG.9; 71/11; 424/93.51; 424/94.61; 424/94.63; 435/254.1; 435/940; 435/942; 504/100; 504/117 |
| Intern'l Class: |
A01N 063/00; A01C 001/06; C12N 001/14; C12N 001/16; C12N 001/18; A61K 037/54 |
| Field of Search: |
424/93,94.61,94.63
71/11
47/57.6,58,DIG. 9
435/254,255,256,940,942
|
References Cited
| Foreign Patent Documents |
| 1091056 | Dec., 1980 | CA.
| |
Other References
Newsted et al., 1985, Can. J. Bot. 63(12): 2311-2318.
Handoo et al. 1979, Seeds Research 7(2): 151-156.
Norton et al., 1985, Can. J. Bot. 63(6): 1040-1045.
Takeda Chemical Industries, 1981, Chem. Abstr. 94(11): #82202v.
Humphrey, R., 1981, Chem. Abstr. 94(11): #82989g.
|
Primary Examiner: Weimar; Elizabeth C.
Assistant Examiner: Fox; David T.
Attorney, Agent or Firm: Foley & Lardner
Claims
I claim:
1. A seed dressing material effective in enhancing the growth of and trace
element uptake in corn plants, said material comprising effective amounts
of fungal spores of the species Coprinus comatus and GTF chromium.
2. A seed dressing material effective in enhancing the growth of and trace
element uptake in corn plants, said material comprising effective amounts
of fungal spores of the species Coprinus comatus, GTF chromium and yeast.
3. The seed dressing material of claim 2, wherein said yeast is brewer's
yeast or baker's yeast.
4. The seed dressing material of claim 2, wherein said yeast is of the
genus Saccharomyces.
5. The seed dressing material of claim 2, wherein said yeast is
Saccharomyces cerevisiae.
6. The seed dressing material of claim 2 further comprising an enzyme, said
enzyme being selected from the group consisting of amylase, protease,
cellulase and combinations of two or more of said enzymes.
7. The seed dressing material of claim 2 further comprising an energy
source for said yeast.
8. The seed dressing material of claim 1 adapted for treatment of about
25,000 corn seeds or a multiple thereof, and comprising, per 25,000 seeds
to be treated, about 200-300 million Coprinus comatus fungal spores, and
from about 50-100 grams of GTF chromium concentrate containing 2,000
milligrams of GTF chromium per gram.
9. The seed dressing material of claim 2 adapted for treatment of about
25,000 corn seeds or a multiple thereof, and comprising, per 25,000 seeds
to be treated, about 200-300 million Coprinus comatus fungal spores, and
from about 50-100 grams of GTF chromium concentrate containing 2,000
milligrams of GTF chromium per gram.
10. A process for enhancing the growth of corn plants comprising treating
corn seeds with a seed dressing material according to claim 1.
11. A process for enhancing the growth of corn plants comprising treating
corn seeds with a seed dressing material according to claim 2.
12. A method of enhancing trace mineral uptake or growth of a corn crop,
comprising the steps of applying, prior to planting, a seed dressing
material according to claim 1 to seeds of the corn crop.
13. A method of enhancing trace mineral uptake or growth of a corn crop,
comprising the steps of applying, prior to planting, a seed dressing
material according to claim 2 to seeds of the corn crop.
Description
FIELD OF THE INVENTION
This invention relates to agricultural processes, and compositions for use
in agriculture. More specifically, it relates to seed dressing
compositions for application to agricultural crop seeds prior to planting
for enhancement of the growth of crops therefrom, and to processes for
modifying the growth environment of crops, to promote the growth thereof.
BACKGROUND OF THE INVENTION AND PRIOR ART
Crops such as corn and soybeans are grown in North America primarily to
provide a source of animal feed. The flesh and other products from the
animals eventually provide a major source of nutritional human food.
Accordingly, not only is it desirable to promote the rate of growth of
plants and the quantity of edible feed which such plants will yield, but
also it is desirable to ensure that such plants contain quantities of
trace elements required for good human diet.
It is known that a variety of trace elements should be present in human
foodstuffs, to provide a healthy, balanced diet. For example, a certain
minimum level of chromium is desirable. For animal metabolism, chromium
has to be incorporated in a tetra-aquo-dinicotinato compound, called
glucose-tolerance-factor (GTF). Chromium GTF is metabolized in a different
way from inorganic chromium.
Chromium plays a role of considerable significance in glucose metabolism
and in cardiovascular disease. A number of therapeutic trials of human
dietary chromium supplementation have indicated that chromium deficiency
can be a cause or an aggravating factor in the glucose intolerance of
infants suffering from protein calorie malnutrition, of maturity-onset
diabetics, and of middle-aged and elderly subjects. It has been found that
the diets of North American residents tend to be deficient in chromium, to
some extent because a significant constituent of their diet is the meat of
animals which have been corn fed, many of the high yielding corns
traditionally being short of chromium.
Zinc is another trace element which is essential in human diets, in a least
a certain minimum level. Zinc deficient diets lead to anorexia, lack of
growth, and teratogenesis. Zinc is involved in protein synthesis. Its
deficiency in human diets is relatively common.
The presence of zinc in the soil of the growing environment is known to
affect the growth of corn. Literature has taught that if the soil has a
zinc deficiency, then corn plants grown therein tend to be stunted, and
exhibit leaf, stem and root abnormalities. Zinc deficiency in germinating
seeds is especially acute as the seed must carry its entire complement of
zinc if it is to experience growth at temperatures below 17.degree. C.
Zinc deficiency may lead to the death of the plant before the soil warms
up. The application of certain phosphorus-rich fertilizers is known to
cause zinc deficiency in plants. Loneragan et al. (1982), who studied this
zinc-phosphorus relationship, observed that under conditions of high
phosphorus supply and low zinc supply phosphorus is absorbed by the roots
and transported in such excess that it becomes toxic and produces symptoms
resembling zinc deficiency, while not changing the zinc concentration in
the plant tops. Singh et al. (Agronomy Journal, Vol. 78, July-August,
1986) have suggested that increased phosphorus levels may lead to this
reduced zinc uptake via a biological route, namely the reduction of
vesicular-arbuscular-mycorrhizal (VAM) infection of the plant.
Consequently, many commercially available fertilizers contain added zinc
so as to ensure that the soil of the growing environment is sufficiently
rich in zinc prior to planting. The presence of adequate total
concentrations of zinc in the soil of the growing environment does not;
however, necessarily mean that a growing plant will take up the zinc to
the most beneficial extent. Marginal zinc deficiency often goes
undetected, but can have a drastic effect on plant growth.
Mycorrhizal fungi are a special type of fungus commonly present in the soil
which penetrate the root cortex of their specific host plant and
subsequently enter into a symbiotic relationship with the plant. In this
relationship most but not all nutrients essential to the fungus are exuded
from the plant membranes to the fungus, e.g., glucose and amino acids, and
conversely, minerals such as phosphorus, potassium, zinc, calcium, copper,
iron, magnesium, and manganese, are gathered up and delivered to the plant
by the mycorrhiza in a more effective and economic manner than the plant
could have gathered alone.
Hairs called hyphae grow out of the mycorrhiza and associate with the plant
root in arbuscules or tree-like structures at which the nutrient exchange
occurs. The hyphae also extend into the soil t o gather up trace minerals.
There are many varieties of mycorrhiza indigenous to soil, and each is
specific for a particular host. Researchers have attempted to inoculate
soil with a given beneficial mycorrhizal fungus corresponding to a
particular plant. These attempts have met with little success, as these
inoculated varieties lose out in biological competition to the less
effective indigenous mycorrhiza. Accordingly, no enhancement of growth is
demonstrated unless the soil is presterilized. A further problem is that
mycorrhizal fungi suitable for enhancing growth of crops are not, as far
as is known, lab-culturable. This makes their isolation extremely tedious
and costly.
It would be beneficial to the plant that the number of host-specific
mycorrhiza be increased in the vicinity of the seeds and later the roots,
as these fungi increase the uptake of trace minerals to the plant.
It is known that germinating seeds, in addition to producing amino acids
and glucose, produce and exude two volatile compounds, acetaldehyde, a
growth retardant, and ethanol, a growth enhancer. Norton and Harmon
(Canadian J. Bot, Vol. 63, 1985) found that exposure to the volatiles from
aged pea seeds stimulated soil microbial activity. Hyphae grew out from
the mycorrhizal organisms preferentially towards the ethanol exuded from
the aged pea seeds. Ethanol enhances the growth of free-living rhizobia.
It is an object of this invention to provide novel beneficial seed dressing
compositions for application to crop seeds, to enhance symbiotic microbial
benefit with a sugar environment around the seed and GTF chromium as a
nutrient to promote fungi growth and ethanol production.
It is a further object to provide a novel process for growing agricultural
crops.
SUMMARY OF THE INVENTION
The present invention is based upon the discovery that the presence, in the
growing soil environment of cereal crop plants adapted to be grown in an
environment containing or not containing legume growth factor, of spores
of a fungus of a member of the Coprinus family and either GTF chromium or
yeast or combinations thereof, exerts beneficial effects on the growth
characteristics of cereal crop plants. Plants grown in such a soil
environment exhibit faster rates of growth to maturity, increased contents
of beneficial trace elements, especially zinc and phosphorus and grain
chromium, higher yields and a reduction in moisture content.
Whilst it is not intended that this invention should be limited to any
particular theory of the mode of its operation or scientific basis, it is
believed that the aforementioned items of the soil growth environment
operate together to increase the number and activity of the appropriate
mycorrhizal bacteria in the soil with respect to crop growth rate and zinc
and phosphorus assimilation. More specifically, it appears that these
items lead to enhanced ethanol production in the soil, probably as a
result of the fermentation of cellulosic residues and/or glucose plant
exudate in the soil by Coprinus spores, thereby stimulating microorganism
growth such as free living rhizobia and mycorrhiza. Moreover, it appears
to overcome the aforementioned phosphorus-zinc antagonism, probably as a
result of stimulated mycorrhizal activity, so that efficient uptake of
both phosphorus and zinc is experienced by the plant. As a result, the
need for application of phosphorus containing fertilizer can be reduced or
even eliminated.
The plants grown according to the present invention also yield seeds
containing increased zinc contents. In fact, the zinc content of such
seeds is often sufficient to supply the entire need for zinc in the
growing environment of such seeds. This is important since, at
temperatures below about 17.degree. C., growing seeds are unable to
assimilate zinc from the soil environment and must rely on their own zinc
content to supply zinc to the growing plant. Temperatures below 17.degree.
C. are commonly encountered during growing seasons in temperate climates.
Seeds derived from plants grown according to the present invention can
thus be grown to provide plants which do not suffer from zinc deficiency
as a result of encountering low growing temperatures.
A further advantage deriving from the practice of the present invention is
a reduction in the requirement for tillage (ploughing) of the growth soil.
Once a crop has been grown according to the present invention, and
harvested, so that the crop has been established in the field, a
subsequent crop of a legume or similar species can be grown in the same
field without tillage. This reduction in tillage is beneficial in reducing
the extent of soil erosion.
The term "legume-growth-factor" referred to herein was coined by
Agriculture Canada after its discovery in the soil surrounding the roots
of leguminous plants, and describes a hereto incompletely characterized
entity or composition of microorganisms. This legume-growth-factor
enhances the growth of non-leguminous as well as leguminous plants,
although it is with the latter that it is naturally associated and from
which it is obtained. For purposes of this invention, it is easiest used
in the form of soil obtained from the roots of leguminous plants,
preferably soybeans without attempting to isolate it from the soil.
The present invention thus provides, from a first aspect, a seed dressing
material for application to seeds of plants to be grown in soil containing
plant assimilable zinc and legume-growth-factor, to enhance growth thereof
and/or trace mineral uptake therein, comprising effective amounts of
fungal spores of at least one fungus of the family Coprinus, and a further
ingredient selected from yeast and GTF chromium, or combinations thereof.
From a second aspect, the invention provides a process of enhancing the
growth and characteristics of cereal crop plants, which comprises growing
the plant crops from seeds in a soil environment Which includes effective
amounts of fungal spores of a fungus of the family Coprinus,
legume-growth-factor, in the earth or mulch, and a further ingredient
selected from yeast concentrate containing GTF chromium, or combinations
thereof.
The legume-growth-factor may be indigenous to the soil in which the plants
are grown, or may be added thereto as seed dressing or by soil
inoculation.
PREFERRED EMBODIMENTS
The present invention is best put into practice as a seed dressing
material, in which Coprinus spores and GTF chromium are formed into a
mixture, optionally with carriers, in controlled amounts, ready for
application to crop seeds, such as corn, prior to planting. In such a
manner, sufficient and controlled relative amounts of ingredients, even
very small relative amounts thereof, can be applied. The use of a seed
dressing including all of the specified ingredients ensures their
availability in the growth environment, even though limited supplies of
some of them may be available from the soil itself.
In a preferred form of this invention, the fungal spores for inclusion in
the seed dressing material are those from Coprinus comatus, commonly known
as shaggy-mane mushroom, or from Coprinus micaceus. However, the present
invention is not limited to the use of such fungal spores, and
substantially any fungal spores which are easy to grow in quantity under
temperate conditions on decaying or living plant matter are useful.
GTF chromium is a known, commercially available material, manufactured by
Granulation Technologies Incorporated, New Jersey, U.S.A. This organic
complex is formed by the addition of inorganic chromium to yeast cells.
Chemically, it is reported to be tetra-aquo-dinicotinato-chromium.
The yeast for use in the compositions of the present invention may be any
conventional baker's or brewer's yeast. Non-limiting examples of
appropriate yeasts include those of the genus Saccharomyces, in particular
S. cerevisiae, S. bailii and S. rouxii. One of the many yeasts that may be
used is produced under the name "Allyeast" by Alltech Biotechnology
Centre, Kentucky, U.S.A.
Legume-growth factor, hereinabove described, is an as yet incompletely
identified microorganism or group of microorganisms which has the effect
of enhancing the growth of legumes, for example soybeans, alfalfa, clover,
and beans. It is found in soils in which legumes have been grown. For
purposes of the present invention, it is best to use soil which adheres to
the legume plant root when the plant is removed from its growth
environment, and this earth is difficult to remove from the root even by
vigorous shaking. This soil contains the required legume-growth-factor and
can be used as a soil dressing ingredient. However, the present invention
is not limited to the use of legume-growth-factor in an association with
soil, and legume-growth-factor isolated by any appropriate technique may
be used. When the soil for the cereal crop has previously supported the
growth of a legume such as soybeans, alfalfa, clover or beans, it contains
sufficient legume-growth-factor for purposes of the present invention. It
is still, however, preferred to include legume-growth-factor in the seed
dressing composition when used on a non-recent legume growing soil.
Appropriate amounts of fungal spores for incorporation into the seed
dressing material are from about 200,000,000 to 300,000,000 per 25,000
seeds (sufficient for planting one acre). Most preferably, about
250,000,000 spores per 25,000 seeds are used.
The GTF chromium is available as a concentrate, containing 2,000 micrograms
of GTF chromium per gram, and preferably 50-100 grams of such a
concentrate should be applied to the seeds for planting one acre. Where
the chromium is to be supplied through the addition of a yeast, the
following technique should be used. Where air is the seed-selecting and/or
transport agent, the yeast is mixed in 10 ounces of cornstarch paste per
80,000 kernels of corn and allowed to dry on the seed for two hours. When
the seed selection is not air, the yeast may be applied dry. Two ounces of
graphite is preferred as an additive for lubricating the seed.
Appropriate amounts of the legume-growth-factor to be added depend on the
content naturally present in the soil to be planted. Legume-growth-factor
may be coated on the seed with mud from LGF soil up to 24 ounces per
80,000 corn seeds.
The seed dressing material of this invention may be applied to the seeds in
conjunction with a suitable carrier. Suitable carriers for seed dressings
are well known in the art and include substantially any inert,
environmentally harmless substance which will not adversely affect the
performance of any of the active ingredients and will not damage the seeds
or growing plant roots. Cornstarch and graphite are typical specific
examples of carriers. Preferably, enough carrier is present to produce a
usable paste in 10 oz. of water for 80,000 seeds.
Since the purpose of the invention is to enhance mycorrhizal activity, then
the addition of phosphorus is to be so limited that the plant will exude
nutrients to enhance the fungal growth to make phosphorus available. In a
low to medium phosphorus soil, 50 lbs. per acre of monosodium phosphate is
adequate. When the rating for phosphorus is high, the addition of
phosphorus is counterproductive. To the phosphorus may be added 100 grams
of copper 100 grams of boron and 500 grams of zinc. Copper correlates with
chromium and copper and chromium together is known as a systemic fungicide
(although toxic where inorganic chromium is used). Boron is often in
deficiency in a drought situation especially in a high fertility soil such
as this invention produces. In the corn grown using this process, it is
found that the chromium content in the seed correlates negatively with
corn ear mould and also that the application of copper to the soil reduces
ear mould.
In a further embodiment, yield of the plants treated with the compositions
of the present invention may be further improved by the use of an energy
source or by an enzyme which enhances the activity of the yeast.
Preferably, the energy source is molasses added as 2 liters per 25,000
seeds dribbled on the seed in a water-thinned solution as the seed is
planted. Molasses added to the seed treatment will dry in about 5 hours so
that no seed stickiness is apparent. Preferably, the enzyme is selected
from the group comprising amylases, proteases, or cellulases or
combinations thereof. One of the many enzyme formulations that may be used
is produced under the name "Allcoholase II" by Alltech Biotechnology
Centre, Kentucky, U.S.A.
To be most effective, the compositions of the present invention should be
used on seeds in post-legume soil where herbicide has not been used to
kill the legume. This does not rule out continuous corn ground where
improved yields and higher chromium grain content is occurring.
The dressing material of this invention may be applied to the seeds of any
agricultural crop. Especially beneficial results are obtained with corn
crops.
The result of the use of the seed dressing according to the invention
appears to be an enhanced, beneficial mycorrhizal population in the
growing environment. This explosion of the beneficial mycorrhizal
population, and the virulence thereof, may crowd out and destroy some of
the pathogenic microbiological soil population, e.g. those fungi
responsible for seed rot. Accordingly, the use of fungicides, with their
deleterious side effects, may be avoided with the seed dressing of this
invention.
Plants grown in the presence of the seed dressing according to the
invention result in much improved crop yields, crop quality and plant
characteristics. In particular, the growing plants have leaves disposed in
a more erect position ("pineapple effect"), which means they are much more
effective in photosynthesis. The volume of the plant is much greater, at
any given stage of growth, and the phosphorus content of the leaves is
significantly higher. This indicates that the plant is more efficiently
utilizing the phosphorus naturally present in the soil to derive its own
phosphorus growth requirement from the ground, through the mycorrhizal
activity, to the extent that a phosphorus-containing fertilizer does not
need to be applied in many instances. With this invention, there is also a
reduction or elimination of primary tillage, as each field would become
"established" with the correct mycorrhizal population. Any ploughing
activity tends to destroy the mycorrhiza and sterilize the soil. This is
extremely important in terms of erosion control.
The invention is further illustrated in the following specific examples.
EXAMPLE 1
The seeds of two varieties of corn, namely DeKalb 461 and DeKalb 1044 were
coated with seed dressing material according to the invention and compared
with controls.
The planting soil was a clay loam, previously used for soybean growth. No
primary tillage was undertaken. Seeds were treated with 100 mg of GTF
chromium, in a carrier, per acre. Planting took place on May 10, 1986.
During the plant growth, observations were made, and "silking" at a certain
date was recorded. Three replicate samples were measured in each case,
from different locations, and totalled. Silking indicates the coming into
flower of the plant--the greater the number of silks, the greater the
maturity of the plant. These results are shown in Table 1 below and show
variety response in the time it takes to silk.
TABLE 1
______________________________________
Measurement
Silked Non-Silked
Silked
Variety Date Plants Plants Non-Silked
______________________________________
Dek 461 Aug. 2 34 235 1:7
(control)
Dek 461 Aug. 2 156 138 1:1
(treated)
Dek 1044 Aug. 24 176 71 2.5:1
(control)
DeK 1044 Aug. 24 125 152 1:1
(treated)
______________________________________
EXAMPLE 2
The plants grown according to Example 1 were harvested Dec. 1, 1986, and
tested for grain yield (in bushels per acre) by determining the ear
weights and moisture contents thereof. The harvested grain was also
analyzed for zinc content. Again three replicates from different locations
were taken and totalled. The yield was measured at a moisture content of
15.5%. The results are given below in Table 2.
TABLE 2
______________________________________
Avg.
Total Ear Yield B/A Moisture
Zinc
Variety Wt. (Kg) at 15.5% Content %
(ppm)
______________________________________
Dek 461 31.6 140 17.0 22
(control)
Dek 461 37.1 166 15.8 29
(treated)
Dek 1044
37.3 160 21 no
(control) difference
DeK 1044
44.8 186 21 no
(treated) difference
______________________________________
Thus, the treatment with the seed dressing of this invention is responsible
for a 16-18% yield increase in these corns, and about a 30% increase in
zinc content with DeK 461. The lower moisture content in the case of 461
is also noteworthy, as indicating better mold resistance. Both in terms of
its growth rate to maturity (as shown by silking reported in Example 3)
and zino uptake, the variety DeK 461 responds better to the invention than
DeK 1044. However, the increase in yield is demonstrated by both
varieties. The moisture difference from 17.0% to 15.8% on December 1st
means the treated corn could be sold or stored as dry from the field. The
control would have to have a drying fee.
EXAMPLE 3
Corn seeds were planted in seed pots in the presence and absence of the
seed dressing material according to the invention. The roots of the corn
plants were then examined for surrounding hair growth.
In the control experiment, where no seed dressing had been applied to the
germinating seeds, the roots were bald, white and hairless, and had no
soil clinging to them.
In the trial experiment, where seed dressing had been applied to the
germinating seeds, the roots were covered with root hairs and contained
abundant soil clinging to the roots. The adhering soil is the formation of
soil structure.
EXAMPLE 4
Corn seeds were grown in the presence and absence of the seed dressing
material according to the invention, harvested, and the leaves of the
plants analyzed for the trace element phosphorus.
In a first control experiment, the corn was planted and grown in a soil in
which corn had previously been grown. In a second control experiment, the
corn was planted and grown in a soil to which crop rotation had been
applied, the previous crop having been soybeans. In the first trial
experiment, (experiment A), the soil was in accordance with the first
control experiment but the seeds were treated with the seed dressing
material in accordance with this invention. In the second trial
experiment, (experiment B), the soil was in accordance with the second
control experiment but the seeds were treated with the seed dressing
material in accordance with this invention.
The seeds were all planted at the same time, and grown to maturity, then
harvested, Leaves from the plants were separated, lyophilized and ground
to powder, then subjected to Nuclear Activation Analysis (NAA), to
determine the quantity of phosphorus therein. NAA analysis is a recognized
analytical technique wherein a sample of material is placed inside a
nuclear reactor, irradiated, and subsequently tested for re-irradiation.
TABLE 4
______________________________________
Control Control Experiment Experiment
1 2 A B
______________________________________
Phosphorus
3.71 2.18 5.54 6.98
content
mg/g
______________________________________
As indicated in Table 4, there is a 149% increase in phosphorus levels in
the trial group over the controls in corn grown on continuous corn soil,
and a 320% increase in phosphorus levels in the trial group over the
controls in corn grown in soybean soil.
EXAMPLE 5
Twelve varieties of corn seed were set out in a modified Latin square of
three replicates each and treated with the seed dressing material in
accordance with the invention (Coprinus comatus spores, GTF chromium
concentrate, legume-growth-factor innoculum, corn starch) and three not
treated (control). The corn was planted in a soil in which corn had
previously been grown. No phosphorus or potassium fertilizer was added to
the soil but nitrogen was applied in the form of NH.sub.3. The plot was
manured using liquid manure. Kernels from the mature corn plants were
analyzed for chromium content using a "dry-ashing" technique and then
Nuclear Activation Analysis. Dry ashing is a state of the art technique in
which the sample material is oven-dried in polyethylene containers and
then heated in a muffle furnace at 450.degree. C. Dry-ashing removes
carbon from the samples and thus greatly improves the accuracy of chromium
determination (see Vuori and Kumpulainen, 1987). The test results are
indicated in Table 5 below.
TABLE 5
______________________________________
Chromium level in ppm
Seed variety Treated Control
______________________________________
DeK 397 1.10 .55
DeK 415 .66 .44
DeK 524 1.00 .67
DeK 362 .73 .16
DeK 437 .37 .20
DeK 445 .25 .13
DeK 484 trace .31
Golden Harvest 1646
.27 .36
Golden Harvest 1826
1.20 .41
Golden Harvest 2300
.53 .40
Golden Harvest 725
.99 .42
Golden Harvest 2344
.57 .18
______________________________________
MAXIMUM ERROR = +/- .07
MINIMUM ERROR = +/- .04
As indicated in Table 5, ten of the twelve varieties of corn analyzed
measured higher in chromium content for treated samples as compared with
untreated samples.
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